Removal and Detection of Algae, Their Toxins, and Excess Nutrients

ABSTRACT

A method of removing from water at least one of algae, bacteria, toxins produced by algae, toxins produced by bacteria, and algae nutrients by placing an open-cell foam material into the water, leaving the material in the water for sufficient time to adsorb/absorb at least one of algae, their toxins, and their nutrients, and then removing the open-cell foam material from the water.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of Provisional Application62/735,302 filed on Sep. 24, 2018, the entire disclosure of which isincorporated herein by reference.

BACKGROUND

This disclosure relates to the removal of harmful materials from bodiesof water using an open-cell foam material.

Harmful algal blooms (“HABs”) occur when colonies of algae, whichincludes cyanobacteria (sometimes referred to as “blue-green algae”)grow out of control. HABs produce toxins (commonly referred to ascyanotoxins) which cause harmful effects on people, mammals (e.g.,dogs), fish, shellfish, marine mammals, birds, and other life.Cyanotoxins usually target the nervous system, the liver, or the skin.

HABs are occurring more often and in locations not previously affectedas a result of climate change and increasing challenges withuncontrolled discharges of excess nutrients (mainly phosphorus andnitrogen) into bodies of water.

Among cyanotoxins are some of the most powerful natural poisons known,including poisons which can cause rapid death by respiratory failure.The toxins include potent neurotoxins, hepatotoxins, cytotoxins, andendotoxins. Recreational exposure to cyanobacteria can result ingastro-intestinal and hay fever symptoms or skin rashes.

Exposure to the cyanobacteria hepatotoxin Microcystin (MC) can causeserious damage to the liver. Acute health effects include abdominalpain, vomiting and nausea, diarrhea, headache, blistering around themouth, and after inhalation sore throat, dry cough, and pneumonia.

Exposure to the cyanobacteria neurotoxin BMAA may be an environmentalcause of neurodegenerative diseases such as amyotrophic lateralsclerosis (ALS), Parkinson's disease, and Alzheimer's disease.

Much of the coastline and bodies of fresh water (even in the mainland)throughout the world experience HABs. These blooms are a global problembecause they affect not only the health of people and marine ecosystems,but also the economy.

Practical, cost effective, scalable, and efficient solutions to removeexcess nutrients in water that facilitate HABs have been relativelynon-existent. Additionally, solutions to cost effectively andefficiently mitigate HABs and related cyanotoxins without moving thedangerous cyanotoxins from one body of water to another (e.g., from apond to an underground injection well) and/or from a body of water to alandfill have also been relatively non-existent.

Furthermore, chemicals or other substances that mitigate and/or kill theHABs are known to also kill aquatic life and/or pose risks to humanhealth among other mammals such as dogs and in some cases, protectedwildlife.

SUMMARY

The methods of removing algae, bacteria, their toxins, and/or excessnutrients contemplate placing an open-cell foam material in the watersuch that the open-cell foam material takes up the algae, bacteria,their toxins, and/or their nutrients. When the material is removed fromthe water, the algae, the bacteria, their toxins, and/or excessnutrients are removed. The use of the material is thus effective toreduce contamination levels in the water. Also, biochar can beincorporated into the foam and/or used by itself, separately, with thefoam configurations.

Attributes of the methods include:

-   -   Passive or non-invasive, meaning no leaching of chemicals.    -   Renewable/sustainable in that once the open-cell foam is        saturated it can be transported to a waste-to-energy facility        where the foam is burned, thereby destroying the toxins without        impacting another body of water or moving the toxins to a        landfill.    -   Renewable/sustainable in that when biochar is included (either        embedded in the foam or in a self-contained (e.g. an 8″ diameter        sock with a 12″ length) device attached to and/or alongside the        open-cell foam, the biochar with adsorbed/absorbed nutrients can        be used to help restore impaired soils.

In one aspect, a method of removing from water at least one of algae,bacteria, toxins produced by algae, toxins produced by bacteria, andalgae nutrients, includes placing an open cell foam material into thewater, leaving the material in the water for sufficient time toadsorb/absorb at least one of algae, bacteria, their toxins, and excessnutrients, and then removing the open-cell foam material from the water.

The toxins may be produced by cyanobacteria. At least about 1,000 ppb ofthe toxins may be removed. At least about 250,000 ppb of the toxins maybe removed. Algae may be removed. Microcystins (MC) may be removed.Cyanobacteria may be removed. The foam may comprise EMA or a blend ofEngage/metallocene or single site initiated polyethylene and LDPE.Phosphorus may be removed. The method may further comprise placing abiochar into the water with the foam. The biochar may be incorporatedinto the foam and/or it may be deployed in conjunction with the foam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one non-limiting example of the placement of open-cellfoam material into a body of water.

FIG. 2 schematically illustrates a combined foam/biochar contaminantremoval device.

DETAILED DESCRIPTION

Featured in this disclosure is the use of open-cell foam materials toremove from water excess nutrients for HABs and/or HABs, and/or theassociated cyanotoxins produced and/or released by the HABs. Theopen-cell foam materials can comprise or be made from polyolefins (e.g.,polyethylene, low-density polyethylene, and/or Engage polyolefin fromthe Dow Chemical Company), polyurethanes, ethylene-alkyl acrylatecopolymers such as EMA, EMA-polyolefin blends, and other foamed polymerswith open (as opposed to closed) cells. Materials that can be usedinclude but are not limited to the open-cell foam materials disclosed inthe following U.S. patents/published patent applications, the entiredisclosures of which are incorporated herein by reference for allpurposes: U.S. Pat. No. 8,853,289; 2013/0240451; 2017/0146435;2017/0241870; and 2019/0017983.

The open-cell foam materials are able to remove from water HABs,cyanotoxins, and excess nutrients such as phosphorus that effectively“feed” the HABs. The open-cell foams' chemistry, open-cell surface areaand capillary network are effective to absorb these HABs, excessnutrients, and toxins into the open-cell capillary network by adsorbingthem to cell walls and thus removing them from the waterway.

Furthermore, the foam can remove and detect food sources for what isknown as blue-green algae/cyanobacteria, including phosphorous. Bydeploying various designs of fabricated open-cell foam it iscontemplated that phosphorous can be effectively removed to assist inthe prevention of blue-green algae/cyanobacteria blooms. One suchembodiment is a flow-through container (like a sock or a mesh container)that contains both the foam and the biochar, and that is left in ormoved through the water. This filtration device can be used to removeall other substances that are referenced in this disclosure, in variousbodies of water.

In one aspect, this disclosure features a method of detecting thepresence of and/or of removing from water HABs, bacteria, their toxins,and their excess nutrients. In the methods, an open-cell foam materialis placed into the water (e.g., placed on the surface, placed under thesurface, or moved up and down in the water column and/or side to side onthe surface or in the water column). The foam material (with or withoutbiochar that can be incorporated into the foam or deployed together withthe foam) is left in the water for a time, and then removed. The removedfoam material can then be (but need not be) tested for removedmaterial(s), in some cases using an EPA-approved test procedure. Thetesting may be for HABs, toxins produced by HABs, and/or nutrients thatare used by HABs. Testing is not necessary for the removal of harmfulmaterials, but is helpful to establish what was removed and the efficacyof the method. The contaminated foam can be burned (e.g., in a waste toenergy plant), in order to destroy the HABs, toxins, and excessnutrients. The contaminated foam can be disposed of in other ways aswell.

FIG. 1 depicts three groups of strips or “blades” of open-cell foammaterial 12, 14 and 16. Each group has multiple strips that are heldtogether at about their centers. The groups are fastened to a line 32that is held on the bottom 24 of water body 20 by weight or anchor 30.In this example group 16 floats on the water surface 22, while groups 12and 14 are held at different depths below the surface. This disclosureallows for the placement of open-cell foam material at any one or moreheights of a body of water, and at one or more locations in the body ofwater. Various non-limiting methods of exposing the open-cell materialto water are described herein; any such method can be used as desired oras necessary depending on the body of water, and/or the contaminantremoval or testing regime that is desired under the circumstances.

After desired exposure times, one or more portions of the foam material(or all of the foam material) are removed from the water. This can bedone by clipping or cutting a piece of foam, or removing an entire groupor other portion or separate piece of foam, for example. The exposuretimes can be from seconds to minutes to hours to days to weeks tomonths, depending on the particular testing/removal regime. Since theopen-cell foam absorbs and adsorbs algae, bacteria, their toxins, andtheir nutrients, if desired the removed portions of the foam can betested for particular removed contaminants/materials. The foam can actas an accumulator for these contaminants. Also, the different locationsand different exposure times allow for a tailored review ofcontaminants, their locations, and their movement within the water.

FIG. 2 depicts a contaminant-removal structure 50 comprising a sock orother container (either hard or soft/flexible) 58, through which watercan permeate and flow. The size of the openings in container 58 areselected such that any material inside will not pass through the wall.Inside can be one or both of foam material and biochar. In theillustrated example there are pieces and/or strips of foam material (54and 56, respectively) interspersed with biochar particles 58 (indicatedby small dots). The foam may or may not contain biochar, and/or thebiochar can be included separately from the foam. Structure 50 can beused in addition to or in place of the foam structures shown in FIG. 1.

Following are some test result data for tests using the foam materialsto remove HABs, their toxins, and their nutrients from bodies of water.

Test I: MC Removal

Nine open-cell foams were floated on a river in Florida that wasexperiencing a cyanobacteria bloom. The foams were left in the river for4-6 hours. The foams were made from EMA or from an Engage/low-densitypolyethylene (LDPE) formulation. In the foam testing (reported below),all tested foam configurations had absorption of HAB toxins (in thiscase microcystins or MC) in the range from 45,000 ppb-259,000 ppb (ppbreported as ppb toxins per dry weight of foam). The open-cell foamconfigurations were deployed directly in HABs in the river forapproximately 4-6 hours. The analysis of the samples was performed by athird-party EPA and state-approved independent laboratory using U.S. EPAMethod 546 and Ohio EPA DES 701.0. Testing can be accomplished followingguidelines of the Florida DEP and U.S. EPA, or other established testingguidelines.

The data and analysis results of Test I are partially summarized asfollows:

Of the nine samples, consisting of various open-cell foamcompounds/product configurations, seven had over 100,000 ppb of MCabsorbed into the open-cell foam matrix.

The four samples that showed the highest MC toxin removal values were:

-   -   a. Large-Cell (1.5 mm-3.5 mm cell size) EMA Pad. Size 72″        long×12″ wide×0.25″ thick. 259,000 ppb of MC toxins adsorbed.    -   b. Medium-Cell (1.0 mm-2.5 mm cell size) Engage/LDPE WaterBug.        247,000 ppb of MC toxins adsorbed. A waterbug is an assembly of        foam strips having dimensions of approximately 0.25×0.25×4″ that        are fixed together at their centers to create an assembly that        looks like a porn-porn, as depicted in FIG. 1.    -   c. Large-Cell (1.5 mm-3.5 mm cell size) EMA Roll. 236,000 ppb of        MC toxins adsorbed.    -   d. Large-Cell (1.5 mm-3.5 mm cell size) EMA Eelgrass. 196,000        ppb of MC toxins adsorbed.

For additional context to understand the significance of these results,in 2015 and 2016, the EPA released Health Advisories related to HABs andcyanotoxins/microcystins. The HAB metrics help establish relevantbenchmarks and context. For drinking water, in 2015 when instantaneousgrab samples are used, the EPA Health Advisory set the concentrationlimit at 1.6 ppb for health guidelines for adults and children. In 2016,for recreation and non-potable water, the EPA Health Advisory set thegrab-sample concentration limit at 4 ppb. Note that one should notcompare any health recommendations as to the concentration levels inwater itself directly to the uptake of the toxins into the open-cellfoam capillary network or matrix. However, these data illustrate theimportance of removing the toxins from the water (because 4 ppb is thethreshold for certain health advisories for non-potablewater/recreation) and the importance of removing the toxins from waterby concentrating the toxins into the open-cell foam capillary network.

Test II: MC Removal

Drinking water health advisories as set by the EPA are currently 0.1 ppbof total MC for children and 1.2 ppb of MC for adults.

In another example, whole lake water was taken from an HAB contaminatedpond in Barnstable, Mass., USA. The water was used as a control toestablish a baseline of known microcystins in the water. Themicrocystins in the control were 0.077 ug/l (ppb) as analyzed and testedunder EPA method 546. Strips of two different foam formulations (100%EMA, and a 50/50 blend of Engage polyethylene and LDPE) were placed into225 ml of the control water and left floating on the surface for 10hours. After 10 hours, the foam matrix was removed from the controlwater and then the remaining water was tested to determine how much ofthe microcystins were removed from the control water. Also, the foam wassqueezed manually to remove water from the foam, and the removed waterwas tested for MC level.

The MC level in the control water was 0.077 ppb. The MC left afterexposure to the EMA foam was 0.047 ppb (a MC reduction of 39%), and theMC left after exposure to the 50/50 blend foam was 0.031 ppb (a MCreduction of 60%). The water removed from the EMA foam had 0.356 ppb MC,and the water removed from the 50/50 blend foam had 0.380 ppb MC.

In a second set of tests, the control water was concentrated such thatits MC level was 3.516 ppb. The concentrated control water was thensubjected to the same tests as above. The MC left after exposure to theEMA foam was 2.891 ppb (a MC reduction of 18%), and the MC left afterexposure to the 50/50 blend foam was 2.275 ppb (a MC reduction of 35%).The water removed from the EMA foam had 12.972 ppb MC, and the waterremoved from the 50/50 blend foam had 15.619 ppb MC.

Test III: Algae/MC Removal

Identifying and measuring algae (which includes bacteria such ascyanobacteria) or algal biomass in water can be done with a variety ofmethods including but not limited to the methods outlined herein. Anyaccepted method including EPA methods and other established laboratorymethods can be used to measure and identify the algae and/or algalbiomass contained therein. Algal biomass is the amount of algae in awater body at a given time. For example, cyanobacteria contain a pigmentnamed phycocyanin which is any group of blue, photosynthetic pigmentspresent in cyanobacteria. One method to measure algae is using afluorimeter to identify and measure these blue pigments in the biomassor algae absorbed into the open-cell foam.

Methods that can be used to identify and measure algae and/or algalbiomass herein include but are not limited to: Counting methods thatinclude the use of a microscope or coulter counter. In vivo methods thatinclude Nephelometry, Spectrophotometric attenuance, and fluorescence invivo. Chemical methods that include reducing capacity (carbonequivalent), Spectrophotometry (Ch1 a extract), and Fluorometry (Ch1 aextract).

In this testing, an open-cell foam in the form of a WaterBug® was placedinto Santuit Pond in Mashpee, Mass., USA and moved throughout the watercolumn (including movement over the surface of the water). The pond hadknown problems with HABs (harmful algal blooms). The open-cell foam wasremoved after 20 minutes of exposure to the entire water column and sentto an independent laboratory for testing using AMNIS flow cytometry formeasuring the cell counts and/or algal biomass. Enzyme linkedimmunosorbent assay (“ELISA”) was used to detect and measureMicrocystins and Noduralins toxins.

The open-cell foam tested for live cells per ml were 149 billion cellsper ml. The open-cell foam tested for dead cells per ml were 299 billioncells per ml.

The pond water contained 0.296 ppb of MC. The water was squeezed out ofthe foam and analyzed, and contained at least 26.3 ppb of MC (some mayhave stayed in the open-cell foam) or 88.85 times the concentration inthe base pond water. This lab testing along with the previous testing inthe preceding paragraphs clearly illustrates the ability of the subjectinvention to remove, detect, and concentrate into the open-cell foammatrix algae, algal biomass, and toxins produced by HABs.

In another aspect of this disclosure, biochar is used together with theopen-cell foam. The biochar can be incorporated into the open-cell foamitself (e.g., by mixing biochar into the polymer material before it isfoamed), and/or the biochar can be deployed in a separate configuration(e.g. 8″ diameter sock with a 12″ length) attached/connected to theopen-cell foam in the water. The open-cell foam also helps to preventthe biochar from sinking in the water column. A biochar is disclosed inU.S. Pat. No. 9,878,924, the disclosure of which is incorporated hereinby reference.

Biochar is a charcoal that can be used as a soil amendment. Biochar is astable solid, rich in carbon, and can endure in soil for thousands ofyears. Like most charcoal, biochar is made from biomass via pyrolysis.Biochar is under study as an approach to carbon sequestration as it hasthe potential to help mitigate climate change. It results from processesrelated to pyrogenic carbon capture and storage (PyCCS). Independently,biochar can increase soil fertility of acidic soils (low pH soils),increase agricultural productivity, and provide protection against somefoliar and soil-borne diseases. Biochar is defined by the InternationalBiochar Initiative as “The solid material obtained from thethermochemical conversion of biomass in an oxygen-limited environment.”

A number of implementations have been described. Nevertheless, it willbe understood that additional modifications may be made withoutdeparting from the scope of the inventive concepts described herein,and, accordingly, other examples are within the scope of the followingclaims.

What is claimed is:
 1. A method of removing from water at least one ofalgae, bacteria, toxins produced by algae, toxins produced by bacteria,and algae nutrients, comprising: placing an open-cell foam material intothe water; leaving the material in the water for sufficient time toadsorb/absorb at least one of algae, bacteria, their toxins, and excessnutrients; and then removing the open-cell foam material from the water.2. The method of claim 1, wherein the toxins are produced bycyanobacteria.
 3. The method of claim 1, wherein at least about 1,000ppb of the toxins are removed.
 4. The method of claim 1, wherein atleast about 250,000 ppb of the toxins are removed.
 5. The method ofclaim 1, wherein algae is removed.
 6. The method of claim 1, whereinmicrocystins are removed.
 7. The method of claim 1, whereincyanobacteria are removed.
 8. The method of claim 1, wherein the foamcomprises EMA or a blend of Engage and LDPE.
 9. The method of claim 1,wherein phosphorus is removed.
 10. The method of claim 1, furthercomprising placing a biochar into the water with the foam.
 11. Themethod of claim 10, wherein the biochar is incorporated into the foam.12. The method of claim 10, wherein the biochar is deployed inconjunction with the foam.